The present invention relates generally to a method and apparatus for handling liquid waste, and more specifically to a method and apparatus for preventing the formation of a solid or semi-solid layer on the surface of liquid waste contained in a wet-well.
Wet-wells are closed holding tanks for liquid waste products. Wet-wells are typically formed of concrete or fiberglass and are generally buried or have a substantial portion disposed below ground level. In residential use, several homes or subdivisions may be connected to a single wet-well depending upon the size and capacity of the wet-well. Often, in commercial use, several commercial establishments are connected to a single wet-well. The wet-well receives liquid waste, rain run-off, sewage, surfactants, and any other waste products that a home or establishment xe2x80x9cflushesxe2x80x9d down a drain.
Wet-wells may also be part of a sewer collection system where a plurality of wet-wells, possibly of differing sizes, are connected to each other in various configurations The final destination of the liquid waste in the sewer collection system is the municipal sewage treatment facility.
Unfortunately, waste products that ought not enter the drainage system are nonetheless discarded inappropriately. For example, restaurants are not permitted to flush waste cooking oil and grease down the drain, but some establishments do so in contravention of local ordinances. Such waste products combine with other waste products and tend to form a solid or semi-solid layer on the surface of the liquid waste in the wet-well. It has been found by observation that in some wet-well systems, such a solid or semi-solid layer may be two feet thick or greater. This causes failure of the wet-well function and necessitates costly repair and maintenance. Accordingly, it is desirable to have a method and apparatus that prevents the formation of a solid or semi-solid layer on the surface of the liquid waste in the wet-well.
The disadvantages of present sewer collection system wet wells are substantially overcome with the present invention by providing a novel method and apparatus for handling liquid waste in the receiving wet-well.
More specifically, one embodiment of the present invention for preventing formation of a solid or semi-solid surface layer in liquid waste contained in a wet-well includes an air pump adapted to pump air into the wet-well and an air pump controller configured to activate and deactivate the air pump at selected times. Also included are a plurality of air injectors disposed in the wet-well and operatively coupled to the air pump. The air injectors inject air into the liquid waste causing a stream of air bubbles to rise in the liquid waste. The air pump controller activates the air pump for a predetermined period of time so that the stream of air bubbles produced within the liquid waste causes turbulence within the liquid waste so as to disrupt and break up solids or semi-solids on a surface of the liquid waste to prevent the formation of the solid or semi-solid surface layer.